The present invention relates to an NMR (Nuclear Magnetic Resonance) imaging or a computed tomography method and apparatus for diagnosis of a body utilizing NMR phenomena, and more particularly to an NMR imaging method and apparatus in which respiratory motion artifacts are reduced.
An NMR imaging apparatus requires a time of about 2 to 20 minutes for imaging. Therefore, the apparatus has a problem that when the breast or abdomen is to be imaged, a blurred image and/or artifacts is produced due to the influence of respiration. In order to avoid this problem, M. L. Wood et al have proposed in "Suppression of respiratory motion artifacts in magnetic resonance imaging", Med. Phys. 13 (6), November/December 1986 (1) a method of detecting a respiratory motion for synchronization therewith and (2) a method of interchanging the order of measurement of data (or the order of application of phase encoding pulses) in accordance with a respiratory motion. However, each of these methods requires the addition of a special hardware exclusively used for detecting the respiratory motion and inhibits efficient operability for performing an imaging. Examples of a method of detecting the respiratory motion include (1) an air bag method in which the respiratory motion is detected utilizing a phenomenon that the pressure in an air bag fixed on the abdomen changes depending on the respiration, (2) a band method in which the respiratory motion is detected utilizing a phenomenon that a tube filled with a solution of zinc sulfate and banded or wound around the abdomen expands depending on the respiration with a change in electric resistance of the tube, and (3) a thermistor method in which a thermistor is attached near the naris to detect a temperature which changes depending on the respiration.